<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2020-06-04</periodOfReport>

    <dateOfOriginalSubmission>2020-06-18</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0000922621</issuerCik>
        <issuerName>ERIE INDEMNITY CO</issuerName>
        <issuerTradingSymbol>ERIE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001657922</rptOwnerCik>
            <rptOwnerName>Pelkowski Julie Marie</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 ERIE INSURANCE PLACE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ERIE</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>16530</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>SVP, Controller</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>525.88</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Incentive Compensation Deferral Plan Share Credits</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-06-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>449.759</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>180.90</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F4"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>449.759</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1604.692</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Conversion price is not applicable to shares granted under the Erie Indemnity Company Incentive Compensation Deferral Plan.</footnote>
        <footnote id="F2">Acquired under the Erie Indemnity Company Incentive Compensation Deferral Plan from a Long Term Incentive Plan award.</footnote>
        <footnote id="F3">A de minimus adjustment to correct rounding of share amount.</footnote>
        <footnote id="F4">The shares subject to this reporting are Share Credits which are periodically credited to the accounts of a select group of management and highly compensated employees of Erie Indemnity Company pursuant to its Incentive Compensation Deferral Plan. ??These Share Credits represent the right to receive an equivalent number of shares of Erie Indemnity Company Class A common stock when the reporting individual retires or otherwise separates from service with the Company.? There are no exercisable or expiration dates for these securities.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Rebecca A. Buona, Power of Attorney</signatureName>
        <signatureDate>2020-07-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
